The present invention generally relates to the field of power converters, and more particularly to a dual input AC and DC to programmable DC output power converter.
As the use of mobile electronic products, such as PC notebooks, PDAs, cellular telephones and the like, continues to increase, the need for low cost, compact power supplies to power and recharge these products also continues to increase. Most manufacturers of mobile products typically include plug-in power adapters along with these mobile products to help facilitate the power supply needs of their customers.
Today""s power adapters are typically AC-to-DC, or DC-to-DC power converters which are configured to either step-up or step-down the DC voltage input delivered to the mobile device. With AC-to-DC adapters, for example, users can power most mobile devices by simply plugging the adapter into a simple AC wall outlet commonly found in most homes or offices. Similarly, when only DC input power is available, such as in an automobile or airplane, users can still power their mobile devices by simply using a standard, off-the-shelf DC-to-DC adapter. Normally, both adapters are designed and tailored to provide a regulated DC output voltage, which typically range from between 5 VDC to 30 VDC depending on the kind of mobile device being powered.
Although these power adapters conveniently provide direct power and recharging capabilities, users are often required to carry separate adapters to provide power to each individual mobile device. This often means that users have to carry multiple adapters: one for an AC input power source, and another for a DC input power source. This often means that users are typically required to carry multiple adapters to power multiple devices. Thus, by carrying multiple mobile devices, users are often forced to carry more than one power supply adapter, thereby increasing the amount of bulk a user is required to carry.
Accordingly, there exists a need for a power converter that resolves the system management problems associated with carrying all of the different power supply components necessary to power a wide variety of mobile or portable devices. Moreover, such a power converter would advantageously encompass serving the power supply needs of several different mobile devices, as it would supply a filtered and regulated DC output voltage in response to either an AC and DC input voltage. Moreover, by having a power converter that has multiple output terminals, users have the ability of providing power to several mobile devices of varying power requirements, simultaneously, regardless of whether the input voltage is AC or DC.
The present invention achieves technical advantages as a power converter capable of supplying dual DC output voltages derived from either an AC input voltage or a DC input voltage, and having a single loop feedback comprised of stacked photocouplers, one coupled to a respective converter. The single feedback loop includes a separate photocoupler, one controlling an AC/DC converter, and the other controlling the DC/DC boost converter, which provides a cost efficient and technically preferable solution. The power converter can be externally programmable to cover a wide range of voltage and current combinations, suitable for a wide variety of mobile product offerings. Moreover, the power converter also resolves the management problems associated with having several different interface components necessary to power a wide variety of mobile products.
In one preferred embodiment, the invention is a power converter having a first circuit adapted to receive an AC input voltage and provide a first programmable DC output voltage. The power converter includes a second circuit adapted to provide a second programmable DC output voltage in response to a DC input voltage. The power converter also includes a third circuit that, in response to receiving the first and second DC output voltages, generates a selectable DC output voltage at a first output. Moreover, the third circuit generally comprises a feedback circuit and is adapted to interface with a removable program module. This programming module feature allows users of the power converter to selectively establish the voltage level of the DC output voltage. Advantageously, the feedback circuit also comprises the single feedback loop which includes a first and a second optical device comprising a pair of photocouplers connected in series (stacked). The feedback circuit is adapted to regulate the selectable DC output voltage generated at the first output in response to the on and/or off status of either series photo-coupler. The power converter also includes a fourth circuit that is coupled to first output. The fourth circuit provides a second DC output voltage as a second output which is independent of, and substantially lower than the selectable DC output voltage.